Acetylene is simplest member of unsaturated hydrocarbons called alkynes or acetylenes. Most important of all starting materials for organic synthesis. Usefulness of actylene is partly due to the variety of addition reactions which its triple bond undergoes and partly due to the fact that its weakly acidic hydrogen atoms are replaceable by reaction with strong bases to form acetylide salts.
Acetylene is a compressed gas that is used as a fuel and is stored in a liquid state. When the valve is opened and pressure is released a portion of the liquid turns to gas. This gas is then used by the device that the cylinder is connected to. Because acetylene is stored as a liquid, the cylinder will only work properly if the tank is used in the upright position. Using, or storing, the tank in any other position can be extremely dangerous. According to the U.S. Department of Labor General Industry
Digest, 1994 (Revised):